1. Field of the Invention
The invention relates to a self-propelled construction machine, in particular a road milling machine, recycler, stabiliser, finisher or roller, comprising a machine frame, on which a working unit is arranged, and comprising a drive unit for driving the working unit.
2. Description of the Prior Art
In road construction, self-propelled construction machines of different designs are used, including the known road milling machines, recyclers, stabilisers, finishers or rollers. Existing layers of the road surfacing can be removed using the known road milling machines and existing surfaces can be prepared using the recyclers. The stabilisers are used to stabilise soils that do not have sufficient load-bearing capacity, for example for road construction. The finishers are used to build roads, a distinction being drawn between asphalt finishers for laying asphalt and slip form finishers for laying concrete. Rollers are used to compress a wide range of materials in road construction, groundwork, agriculture and landfill construction. Construction machines of this type have a working unit for carrying out the work required for the building operations, which working unit may for example be a working roller, and in particular a milling roller equipped with milling tools in the case of road milling machines, stabilisers and recyclers. The working roller is driven by a drive unit which has at least one internal combustion engine. The fuel for the internal combustion engine, in particular a diesel engine, is provided in a fuel tank, in particular a diesel fuel tank.
Furthermore, it is known that construction machines comprise a water tank for storing service water. This service water is used for example in the known road milling machines in order to ensure that, during the milling process, the milling tools are cooled and thus the service life is increased, or is used in the known rollers in order to remove dirt from the roller lining and thus prevent the work result from being negatively impacted. Along with fuel and water, additional operating materials are also required for the operation of the construction machine. Therefore, in addition to the fuel tank and water tank, the known construction machines also have one or more operating material tanks arranged on the machine frame.
U.S. Pat. No. 2,008,260 461 A1 discloses a self-propelled construction machine comprising a drive unit having two internal combustion engines for the milling roller.
A general problem of construction machines is the limited space available for accommodating all the machine components. The construction machine should have as compact a design as possible in order to be able to keep a sufficiently wide lane open for moving traffic, to be able to be used even in confined spaces and to allow the construction machine to be transported without special permits.
A particular problem of construction machines comprising internal combustion engines is the ever stricter exhaust emission regulations. New exhaust emission regulations make it compulsory for exhaust gases to be treated further by means of additional technology. One known technique for post-treatment of exhaust gases is selective catalytic reduction (SCR). When using construction machines in different countries, the problem still arises of having to comply with various emissions guidelines. The engine technology and exhaust gas treatment technology required to comply with stricter emissions guidelines place high demands on fuel quality, for example low sulphur content, but this cannot be guaranteed in all countries. If fuel of sufficient quality is not available in individual countries, a construction machine having an exhaust gas treatment system cannot be used. It is therefore necessary to produce various designs of construction machines for different countries, the engine technology and exhaust gas technology of which machines are adapted to the respective general conditions. However, producing different configurations increases production complexity, the overall result of which is higher production costs, in particular in the case of small-batch production.
Exhaust gas treatment systems require additives, in particular a urea solution which has to be provided in an additional operating material tank. In one configuration of the construction machine having an exhaust gas treatment system, it is necessary to provide a urea solution, although this is not the case in a configuration without an exhaust gas treatment system. Equipping the construction machine with an exhaust gas treatment system means that changes have to be made to the chassis of the construction machine in order to attach the operating material tank. Otherwise, accommodating an additional tank increases the dimensions of the construction machine.
A sealed double-chamber tank for a motor vehicle is known from DE 10 2011 100 476 A1. The double-chamber tank has a single tank shell which is divided into two chambers. One chamber may hold diesel fuel and the other chamber may hold urea. DE 10 2011 100 476 A1 only describes the double-chamber tank in detail, and not the motor vehicle in which the double-chamber tank is installed. When the double-chamber tank is installed in the motor vehicle, the tank forms a separate component which is supported by the vehicle frame. DE 10 2009 000 094 A1 proposes integrating a tank for receiving a reducing agent in a fuel tank or washing water tank of a motor vehicle; however DE 10 2009 000 094 A1 also does not describe the motor vehicle comprising the fuel tank and the washing water tank in detail.